We had an issue on the hosts in our Hyper-V cluster where after a reboot they would take several minutes to log in, hanging at the Welcome screen. This was causing our cluster to become unstable and failovers of VM’s to occur.

The solution we found was to run devnodeclean on each of the hosts to clear out the Phantom devices stored in the registry hive, as per Microsoft KB982210. We weren’t able to install the hotfix, as we were notified that this update wasn’t applicable when attempting the install (our hosts are kept up-to-date with latest patches).

Download devnodeclean from here. A readme with instructions is provided